1. Field of the Invention
The present invention generally relates to techniques for detection of heart disease, and more particularly to a technique which reveals disorders of the coronary arteries.
2. Description of the Prior Art
Every year, more than 550,000 people die of heart attacks in the United States alone. In fact, heart disease is the number one killer of persons living in the U.S. Heart attacks are usually brought on by the accumulation of fat and other substances within the coronary arteries, those vessels which supply the heart itself with oxygen and nutrient rich blood.
Research scientists are getting closer to the secret of preventing heart attacks. The most important aspect of prevention is detecting the presence of arteriosclerosis before it advances to a critical stage. There are many techniques currently in use for monitoring various cardiac parameters. These include ballistocardiography, electrical impedance measurements, ultrasonics, electrocardiography, and vibrocardiography. These techniques, however, are invasive and require complex, expensive equipment.
Several patents have issued which deal with cardiac screening. For example, U.S. Pat. No. 3,280,817 issued to Jorgensen et al, discloses a method of screening which measures electrical heart activity; however, the effectiveness of this technique depends in large part on the definition of successive function time phases which is extremely subjective. In U.S. Pat. No. 3,048,166 issued to S. Rodbard, another apparatus and method is set forth which records low intensity, high frequency heart sounds; the recording must be played back at a slower speed for enhanced resolution. Also, U.S. Pat. No. 3,762,397 issued to J. Cage describes a similar system. This invention relates only to obtaining a clear trace of the heart sound, erasing any background noise. Finally, U.S. Pat. No. 3,052,756 issued to Seven et al. claims a phonocardiography apparatus which simply records abnormally high frequencies in the electrical undulations of the heart. However, at the present time there are few means for reliable interpretation of the results of these procedures.
It would therefore be desirable and advantageous to devise a simple, safe, and noninvasive method and apparatus for identifying coronary artery disease. The benefit of such a device would be greatly enhanced if it could be used by technicians or other non-medical personnel in screening large groups of people, without the need for a special clinic or hospital facilities. The device and method for detection of coronary artery disease which is the basis of this invention utilizes characteristic sounds produced by the heart.